Free: Contests & Raffles.
Use natural casings . They may take a little more finesse but once you use them a bit its not that big of deal . Think about the best Brat, "Kilbasa", Polish, etc. that you have eaten . Most likely natural casings .Collagen and synthetics have their place for sure . Just not here IMO.There are plenty of commercial spice blends that will give you a good product . But as advised in above post try a bit first , if not in meat at least straight . I would recommend the same for any spice recipe you make yourself.Getting a recipe dialed to your taste is half the fun .Add enough fat when using game meat .Once you get it all cased up let it set under (refrigeration) for 24-48 hours if at all possible before you smoke,cook,or freeze. Dont worry unless you really F it up it will still be good .
The man that runs the meats lab at WSU would probably supply some and he has a boat load of experience, Dan Snyder